Solar-thermal-assisted biomass pyrolysis in an inclined tubular reactor with fluidization-like behavior: Experiments, CFD modeling, and scale-up analysis

Solar-thermal integration offers a promising pathway to decarbonize biomass pyrolysis; however, most solar-assisted biomass pyrolysis studies remain limited to batch or fixed-bed configurations, in which poor gas-solid contact and non-uniform heating limit scalability and product control. This work introduces a novel inclined tubular reactor operating under fluidization-like conditions, enabling continuous pyrolysis with improved gas-solid hydrodynamics and heat transfer tailored for concentrated solar-thermal integration. The reactor hydrodynamics were experimentally characterized using particle image velocimetry in a cold-flow model and validated against Eulerian–Eulerian CFD simulations. Reactive simulations of food waste pyrolysis at 500–700 °C reveal a suspension flow structure comprising a hot, solids-rich near-wall layer and a cooler, vapor-lean upper zone, which suppresses secondary tar cracking. Parametric analysis indicates that under optimal operating conditions (600 °C, reactor length of 3.5 m), the model predicts improved devolatilization rates exceeding tar-cracking rates by two to three orders of magnitude in the hottest regions. Scale-up analysis for a 300,000 t yr −1 food waste processing capacity indicates a thermal demand of ∼17 MW, corresponding to ∼16,000 t CO 2 yr −1 of avoided emissions, with additional net-negative potential via biochar sequestration. The results demonstrate a scalable solar-thermal-assisted pyrolysis concept that bridges batch-scale research and industrial biomass conversion. • Novel solar-heated inclined tubular reactor for continuous biomass pyrolysis. • Fluidization-like gas–solid flow validated by PIV experiments and CFD. • Enhanced heat transfer with spatial suppression of secondary tar cracking. • High liquid yield (∼48 wt%) achieved at optimal temperature and reactor length. • Scalable design enables solar-driven pyrolysis with major CO 2 mitigation.